Spain star Costa appeared in good spirits, even staying behind to help put away equipment after the session.

The rest of the squad have been given time off following Saturday's 3-0 win at Leicester.

The club are confident Costa will not kick up a fuss or even refuse to train like Dimitri Payet, who is trying to force through a move from West Ham to Marseille.

Starsport understands boss Antonio Conte bears no grudge against the Brazil-born forward and is ready to restore him to the starting line-up at Stamford Bridge on Sunday.

Conte was angry when Costa reported the back problem last week, with fitness coach Julio Tous insisting it was just a minor issue.

Costa did not play at the King Power on Saturday but he is generally understood to have a good relationship with Chelsea's Italian coach, who was instrumental in talking him out of a return to Atletico Madrid in the summer.

Costa is on around £150,000 a week - he is tied to the club until the summer of 2019 - and Abramovich has no immediate plans to sanction new contract talks.

But Chelsea might look at improving Costa's terms in the summer, particularly if his goals are instrumental in them reclaiming the title.